Hot Weather Turns Up the Heat on Engines
This article printed in the Managers Digest of Construction Equipment Magazine in 1995 has the potential to save fleet operators more money than any other article we've come across when understood and acted upon.
Hot Weather Cooling
Above 218 degrees Fahrenheit, engine oil oxides quickly, and the thin film covering rod bearings starts to break down. Lead and aluminum content jumps as bearings shed layers and begin to self-destruct.
Reading Oil Analysis
Here's a lubrication engineering equation even a trade journalist can follow: Crankcase-oil oxidation doubles for every 18 degrees Fahrenheit that engine temperature rises above 200 degrees. It's only important today if you have an engine that was running at the high end of allowable operating temperatures over the winter. When the spring warm-up raises operating temperatures, that engine's oil could thin out in maximum-load positions like rod bearings.
Even if water is circulating and the radiator is kept full, you can see insufficient cooling capacity to keep the oil in shape, says Marianne Cossey, manager of analysis laboratory at Cat dealer Wagner Equipment Co. in Aurora, Colo. The operator may not notice the increase in temperature on the gauge, but if the radiator fins are clogged or scale is building up inside the radiator, you could get long-term engine wear.
"Caterpillar did a study of rod bearing failures and in more than half of the cases there was evidence of overheating in the last 2000 hours of operation," she says. "If the oil analysis history was available, you'd see a spike in oxidation, lead and aluminum. Even after getting the temperature back under control, rod bearings just let go within 1500 hours."
Trained eyes can detect a 20-degree increase in operating temperature from the corrosion, aluminum and lead in an oil analysis trend line.
"The overheating we see this time of year is typically not hot enough to endanger the engine," says Cossey, "but if you stop the problem now, you've saved a significant impact on engine life."
When ambient temperatures climb erratically into the 60's and 70's, Cossey and her crew of analysts keep a lookout for bumped aluminum and lead qualities.
"If you overheard the things we're telling customers to do who turn in these suspect oil samples (blow out radiators, check for scale), you'd think we worked for a radiator shop, not an oil analysis lab," says Cossey.
This article appeared in the MANAGERS DIGEST of Construction Equipment Magazine - April 1995 issue.
